1. Field of the Invention
The invention relates to a method and apparatus for producing a wave winding for stators of electrical machinery. More particularly, this invention is for a method and apparatus for producing a wave winding where a winding wire is wound onto shaping elements arranged in a circle and acquires a wave shape between the shaping elements.
2. Discussion of Related Technology
In the manufacture of stators, it is common practice to prefabricate coils on a template, strip them in a puller and then pull them axially into the stator slots. Producing and transferring a wave winding directly over the pulling tool or transfer tool causes difficulties.
A process and apparatus for winding and placing a wave winding in the slots of stators are described in DE-PS 33 43 390. There, a first complete coil is wound onto a set of first shaping elements arranged in a circle, and subsequently a set of second shaping elements is moved from the outside against the coil and deforms it. In the same pass with the radial stroke of the second shaping elements, the first shaping elements must yield until a wave winding is shaped. Other publications are also known which have similar designs. All these devices have one thing in common: they first wind a roughly round coil with several turns and then deform them, i.e., all turns together, into a wave winding. This method is very expensive and susceptible to problems, since the device consists of a host of movable parts. To obtain uniform quality of a wave winding, the first shaping elements must be moved synchronously with the second shaping elements during forming, or they must be equipped with expensive damping tubes.
A device for winding and placing coils in the slots of stators of electrical machinery is also described in DE-AS 23 51 952. There, a winding wire is wound circularly from a delivery tube onto first and second shaping elements arranged in a star shape to form a winding. Below the star-shaped arrangement of the first and second shaping elements is a coil pulling device. The first shaping elements consist of a section which bears the winding and a drawing section located above it at a distance. The second shaping elements are made essentially cylindrical and are bent downwards towards the coil pulling device. The second shaping elements project in part into the interior of the circle which is formed by the fingers of the coil pulling device which are located at an interval adjacent to one another. After a preliminary winding has been formed or placed on the first and second shaping elements, the first shaping elements, located between the second shaping elements each move downward, which causes the drawing section to move downwards and fit internally into the winding and draw it downward. While moving downwards, the winding slides over the second shaping elements, which are bent downwards into the intermediate spaces between the fingers of the coil pulling device.
It is a disadvantage in this example that half of the shaping elements move during the forming process and the turns are not shaped in an ordered manner, but rather are wound as a ring-shaped tangle, as the turns move with the first shaping elements and are drawn over the second shaping elements. In doing so, the individual turns are reproduced in an uncontrolled manner and can reach between the fingers of the coil pulling device only with strong tension of the first shaping element. A certain ordering or sequencing of the turns is necessary in order for the turns to reliably reach between the fingers of a coil pulling device.